New trends on photoelectrocatalysis (PEC):nanomaterials, wastewater treatment and hydrogen generation

The need for novel water treatment technologies has been recently recognised as concerning contaminants (organics and pathogens) are resilient to standard technologies. Advanced oxidation processes degrade organics and inactivate microorganisms via generated reactive oxygen species (ROS). Among them, heterogeneous photocatalysis may have reduced efficiency due to, fast electron-hole pair recombination in the photoexcited semiconductor and reduced effective surface area of immobilised photocatalysts. To overcome these, the process can be electrically assisted by using an external bias, an electrically conductive support for the photocatalyst connected to a counter electrode, this is known as photoelectrocatalysis (PEC). Compared to photocatalysis, PEC increases the efficiency of the generation of ROS due to the prevention of charge recombination between photogenerated electron-hole pairs thanks the electrical bias applied. This review presents recent trends, challenges, nanomaterials and different water applications of PEC (degradation of organic pollutants, disinfection and generation of hydrogen from wastewater)

Bench-scale photoelectrocatalytic reactor utilizing rGO-TiO2 photoanodes for the degradation of contaminants of emerging concern in water

Pharmaceuticals and personal care products are contaminants of emerging concern (CEC) in water. Photocatalysis (PC) and photoelectrocatalysis (PEC) are potential advanced oxidation processes for the effective degradation of these contaminants. In this work a bench-scale photoelectrocatalytic reactor utilizing a UVA-LED array was designed and tested for the degradation of diclofenac as a model CEC. Reduced graphene oxide-titanium dioxide (rGO-TiO2) composite, prepared by the photocatalytic reduction of rGO on TiO2, was immobilised on fluorine doped tin oxide (FTO) glass and evaluated as a photoanode. The influence of UVA intensity and rGO:TiO2 ratio on the degradation rate was studied. Surface modification of the TiO2 with 1% rGO gave the highest photocurrent and best degradation rate of diclofenac, as compared to unmodified TiO2. However, following repeat cycles of photoelectrocatalytic treatment there was an observed drop in the photocurrent with rGO-TiO2 anodes and the rate of diclofenac degradation decreased. Raman and XPS analysis indicated the re-oxidation of the rGO. Attempts to regenerate the rGO in-situ by electrochemical reduction did not prove successful, suggesting that the site of photoelectrocatalytic oxidation of rGO was different to the reduction site targeted in the photocatalytic reduction for the formation of the rGO-TiO2 composites

Exploring the design space of nonlinear shallow arches with generalised path-following

The classic snap-through problem of shallow arches is revisited using the so-called generalised path-following technique. Classical buckling theory is a popular tool for designing structures prone to instabilities, albeit with limited applicability as it assumes a linear pre-buckling state. While incremental-iterative nonlinear finite element methods are more accurate, they are considered to be complex and costly for parametric studies. In this regard, a powerful approach for exploring the entire design space of nonlinear structures is the generalised path-following technique. Within this framework, a nonlinear finite element model is coupled with a numerical continuation solver to provide an accurate and robust way of evaluating multi-parametric structural problems. The capabilities of this technique are exemplified here by studying the effects of four different parameters on the structural behaviour of shallow arches, namely, mid span transverse loading, arch rise height, distribution of cross-sectional area along the span, and total volume of the arch. In particular, the distribution of area has a pronounced effect on the nonlinear load-displacement response and can therefore be used effectively for elastic tailoring. Most importantly, we illustrate the risks entailed in optimising the shape of arches using linear assumptions, which arise because the design drivers influencing linear and nonlinear designs are in fact topologically opposed

Experimentally Validated Computational Fluid Dynamics Model for a Data Center With Cold Aisle Containment

This paper presents the results of an experimentally validated computational fluid dynamics (CFD) model for a data center with fully implemented fan curves on both the servers and the computer room air conditioner (CRAC). Both open and contained cold aisle systems are considered in this study. This work is divided into sections for the baseline system (prior to installing containment) calibration and the fully contained cold aisle system calibration and leakage characterization. In the open system, the fan curve of the CRAC unit is extracted from the manufacturer data, while the fan curve of the load banks is obtained through experimental measurements. The experimental results are found to be in good agreement with the average model predictions. In the fully contained cold aisle system, a detailed containment CFD model is developed based on experimental measurements. The model is validated by comparing the flow rate through the perforated floor tiles and the rack inlet temperatures with the experimental measurements. The CFD results are found to be in good agreement with the experimental data with an average relative error between the measured and computed flow rate of approximately 6.7%. Temperature measurements are used to calibrate the sources of leakage in the containment and rack mounting rails. The temperature measurements and the CFD results agree well with an average difference of less than 1 C. This study provides important modeling guidelines for data centers. In order to predict the performance of contained cold aisle systems flow distribution, it is crucial that physics based models of fan curves, server internal resistances, detailed rack models, and other design details are all accurate and experimentally verified

Checkpoint Inhibitors in Multiple Myeloma: Intriguing Potential and Unfulfilled Promises

Immune dysregulation and alteration of the bone marrow microenvironment allowing plasma cells to escape immune surveillance are well-known factors associated with the proliferation of clonal plasma cells and development of multiple myeloma (MM). Whilst immunotherapeutic approaches are now commonplace in a wide spectrum of malignancies, this aberration of myeloma development gives rise to the biological rationale for the use of immune checkpoint inhibitors (ICIs) in MM. However, the initial experience with these agents has been challenging with limited single agent efficacy, significant toxicity, and side effects. Herein, we review the biological and immunological aspects of MM and ICIs. We discuss the basic biology of immune checkpoint inhibitors, mechanisms of resistance, and drug failure patterns, review the published clinical trial data for ICIs in MM, and look towards the future of ICIs for MM treatment

Analysing Agreement Among Different Evaluators in God Class and Feature Envy Detection

The automatic detection of Design Smells has evolved in parallel to the evolution of automatic refactoring tools. There was a huge rise in research activity regarding Design Smell detection from 2010 to the present. However, it should be noted that the adoption of Design Smell detection in real software development practice is not comparable to the adoption of automatic refactoring tools. On the basis of the assumption that it is the objectiveness of a refactoring operation as opposed to the subjectivity in definition and identification of Design Smells that makes the difference, in this paper, the lack of agreement between different evaluators when detecting Design Smells is empirically studied. To do so, a series of experiments and studies were designed and conducted to analyse the concordance in Design Smell detection of different persons and tools, including a comparison between them. This work focuses on two well known Design Smells: God Class and Feature Envy. Concordance analysis is based on the Kappa statistic for inter-rater agreement (particularly Kappa-Fleiss). The results obtained show that there is no agreement in detection in general, and, in those cases where a certain agreement appears, it is considered to be a fair or poor degree of agreement, according to a Kappa-Fleiss interpretation scale. This seems to confirm that there is a subjective component which makes the raters evaluate the presence of Design Smells differently. The study also raises the question of a lack of training and experience regarding Design Smells

Prioritization of god class design smell : A multi-criteria based approach

Context: Design smell Prioritization is a significant activity that tunes the process of software quality enhancement and raises its life cycle. Objective: A multi-criteria merge strategy for Design Smell prioritization is described. The strategy is exemplified with the case of God Class Design Smell. Method: An empirical adjustment of the strategy is performed using a dataset of 24 open source projects. Empirical evaluation was conducted in order to check how is the top ranked God Classes obtained by the proposed technique compared against the top ranked God class according to the opinion of developers involved in each of the projects in the dataset. Results: Results of the evaluation show the strategy should be improved. Analysis of the differences between projects where respondents answer correlates with the strategy and those projects where there is no correlation should be done

Solar photoelectrocatalytic oxidation of urea in water coupled to green hydrogen production

In past decades, the intensification of human activities has led to an increase in pollution and energy demand. Photoelectrochemical systems have emerged as an alternative for the decentralized management of domestic wastewater with the potential of recovering energy while degrading pollutants such as urea. Tungsten oxide (WO3) has been traditionally used for water splitting, but the use of this material for the removal of waste from water coupled to hydrogen production is not deeply known until now. This contribution shows an exhaustive and systematic investigation on WO3 photoanodes for the photoelectrochemical oxidation of urea and the generation of hydrogen, with insights on the reaction mechanism, detailed nitrogen balance investigation of the process, and analysis of the performance compared to well-accepted materials. The WO3 platelets were successfully synthesized in situ on fluorine doped tin oxide glass by a hydrothermal method. The performance of WO3 was compared to titanium dioxide (TiO2) as a benchmark. The photocurrent was enhanced for both electrodes when urea was added to the electrolyte, with WO3 showing one order of magnitude higher photocurrent than TiO2. The WO3 electrode showed a peak incident photon-to-current efficiency of 43% at 360 nm and a much greater rate constant for urea oxidation (1.47 × 10−2 min−1), compared to the TiO2 photoanode (16% at 340 nm and 1.1 × 10−3 min−1). The influence of different reactor configurations was also evaluated testing one- and two-compartment back-face irradiated photoelectrochemical cells. Hydrogen was generated with a Faradaic efficiency of 87.3% and a solar-to-hydrogen conversion efficiency of 1.1%. These findings aim to contribute to the development of technologies based on the photoelectrochemical production of hydrogen coupled with the oxidation of pollutants in wastewater. © 2023 The AuthorsThis work was supported by the European Union’s Horizon 2020 research and innovation programme under the Marie-Curie grant agreement No 812574 (REWATERGY) and under grant agreement No 820718 (PANIWATER). Alvaro ´ Tolosana Moranchel also thanks the Consejería de Educacion, ´ Juventud y Deporte of the Comunidad de Madrid for the Ayuda Destinada a la Atraccion ´ de Talento Investigador (2020-T2/AMB-19927) granted to him. The authors also thank Delft IMP for supporting this research.Supplementary data to this article can be found online at https://doi.org/10.1016/j.jclepro.2023.138200.Peer reviewe